MODULE 1- Studying the Nervous System Flashcards
2 primary cell types of all nervous systems
-neurons
-glia
**neurons
come in a wide variety of sizes, shapes, + the number + complexity of processes (dendrites + axons)
dendrites
part of neuron that RECEIVES information from other neurons
axons
part of neuron that SENDS/TRANSMITS information
**synapse
the point of communication between 2 neurons
neuronal axons are wrapped in ____
myelin
**what creates myelin in the CNS
oligodendrocytes
**what creates myelin in the PNS
Schwann cells
what occurs at the soma of a neuron
protein synthesis
-proteins + organelles must be trafficked long distances to the end of the terminal
**shape of neurons
highly polarized
-a long axon with a distant terminal from which synaptic vesicles release neurotransmitters
axons can be up to how long
1 meter
a taller person has what
longer axons compared to someone that is short
what does a postsynaptic cell have
receptors for neurotransmitters
**divergence
few presynaptic cells to many postsynaptic cells
**convergence
many presynaptic cells to few postsynaptic cells
glia
cells that hold nerve cells in place + help them work the way they should
**glia in CNS
-astrocytes
-oligodendrocytes
-microglia
**astrocytes
-help with blood-brain barrier
-buffer ions + neurotransmitters
-secrete chemicals for synaptogenesis
synaptogenesis
formation of new synapses
-new + more connections between neurons
**oligodendrocytes
myelinate neuronal axons
**microglia
-perform immune function for CNS, considered “immune cells” of CNS
-macrophage activity
-secrete cytokines
**glia in PNS
Schwann cells
**Schwann cells
-myelinate neuronal axons
-participate in recovery of function resulting from neuronal damage
3 ways to visualize neurons in the CNS + PNS
-golgi stain
-flourescent dye
-Nissl stain
-using different stains/dyes can trace how neurons connect to other neurons
-important for understanding how neural circuits are formed
neural circuits
neurons are interconnected in ensembles called neural circuits
-neurons don’t function in isolation but rather work together to form neural circuits
**afferent
towards CNS
-away from periphery/effectors
effectors
muscles, organs, etc.
**efferent
away from CNS
-toward periphery/effectors
**3 ways signals can be classified
-excitatory
-inhibitory
-modulatory
**interneurons
participate in local circuit function
describe axons of interneurons
short axons
myotatic reflex is also called
knee-jerk reflex
myotatic (knee-jerk) reflex is controlled by what
simple neural circuit
reason for myotatic (knee-jerk) reflex
to maintain an upright posture in the face of unexpected changes (such as tripping)
in myotatic (knee-jerk) reflex, flexors are ____ + extensors are ____, causing ____
-flexors are INHIBITED
-extensors are EXCITED
-causing leg extension
describe how myotatic (knee-jerk) reflex occurs
-stimulation of peripheral sensors (a muscle stretch receptor) initiates receptor potentials that trigger APs that travel centrally along the afferent axons of the sensory neurons
-this information stimulates spinal motor neurons by means of synaptic contacts
-the APs triggered by the synaptic potential in motor neurons travel peripherally in efferent neurons, giving rise to muscle contraction + a behavioral response
recording from various places in the reflex loop of the myotatic reflex while responding
-sensory neuron
-interneuron
-motor neuron (extensor)
-motor neuron (flexor)
**optogenetics
a technique for controlling the communication between neurons
-genes for light-sensitive proteins (ex: opsins) are introduced into certain neurons to monitor + control their activity in response to light signals -> chemical signals
circuits that process related information constitute a ____
neural system
neural systems
organization of individual neural circuits according to the type of information they carry into broader networks + larger volumes so that more complex behaviors can be generated
neural systems have ____
unity of function
do neural circuits exist in isolation
no
-found in neural systems
how are neural systems organized
organized into representations of information that are processed in parallel pathways, culminating in topographic maps
computational map
additional information processing based on time or order of input
sensory motor system
neural system that controls how we process sensory information + controls movements
structural analysis of neural systems
-lesion studies reveal the direction of information flow
-labeling specific proteins
neural systems- function
determine what neurons do from moment to moment in a neural system
**receptive field
the region in sensory space to which a neuron will respond
**single unit responding
using single unit responding, it is possible to find the relationship between peripheral stimuli + neuronal responses
example defining relationships between peripheral stimuli + neuronal responses using single-unit recording
-this example is from a cortical pyramidal neuron in the somatosensory cortex of a rhesus monkey, showing the firing pattern in response to a specific peripheral stimulus (pressure applied to a discrete point on the skin surface) in the anesthetized animal
-typical experiment setup, in which a recording electrode is inserted into the somatosensory cortex in the postcentral gyrus
-defining neuronal receptive fields based on the location of the peripheral stimulus in the sensory space (in this case, a particular region of the arm) that elicits the maximal response from the CNS neuron whose AP activity is being recorded, referred to as the receptive field center
-the flanking region (called the surround) is the region of the skin surface that when stimulated will actually diminish the response of the same neuron
**CNS
brain + spinal cord
**PNS
extension of the CNS beyond the brain + spinal cord into the periphery
-consists of everything else outside of CNS, including sensory nerves, motor nerves, spinal + cranial nerves, autonomic ganglia, enteric nervous system, etc.
afferent
PNS sensory info sent to CNS
efferent
CNS motor (visceral + somatic) commands are sent to PNS
motor components consist of what 2 systems
-visceral motor sysem
-somatic motor system
visceral motor system
-sympathetic, parasympathetic, + enteric divisions
-autonomic ganglia + nerves
somatic motor system
motor nerves
effectors
-smooth muscles, cardiac muscles, + gland
-skeletal (striated) muscles
what does the genome control
brain organization + function
how are proteins made
genes (DNA) makes RNA ->
RNA makes protein
**genomics
analysis of the complete DNA sequence of a species or individual
depending on the gene, a single mutation in the DNA can…
have devastating consequences on brain development
what can be analyzed in the human brain
neural circuits + systems
3 things that imaging in the living brain is used for
-discerning various anatomical structures
-diagnoses of medical problems, such as tumor or stroke
-to characterize the activity of the brain as it performs complex tasks, such as problem-solving, recall, speaking, singing, + so much more
minimally invasive analysis of human brain function
-EEG
-TMS
**electroencephalogram (EEG)
can map the brain according to event-related potentials (ERPs)
**transcranial magnetic stimulation (TMS)
used to correlate broad areas of the brain with ongoing behavior
-used for neurologic + psychiatric conditions
-uses electromagnetic coil
radiographic methods for brain imaging
-x-rays
-CT
-PET
**computerized tomography (CT)
x-rays narrowed into a tube sweeps across the brain, providing detailed anatomical structure
**positron emission tomography (PET)
patient is injected with a radio-labeled molecule, such as dopamine, which is then taken up by certain neurons (ex: those of the basal ganglia)
CT or PET is more functional
PET
downside to PET
more invasive, since radioactive isotope is injected
magnetic resonant imaging
-MRI
-DTI
**MRI
ALL YOU NEED TO KNOW- MRI causes hydrogen atoms to act like magnets
-when placed in a magnetic field, a patient (+ his protons (H+)) will line up with the magnetic field + spin at a frequency that depends on the field strength; a brief radiofrequency pulse applied tuned to the atoms’ spinning frequency emit ENERGY as they realign themselves with the field
**DTI (diffusion-tensor imaging)
detects white matter tracts because water molecules can diffuse in limited directions along the length of the axon
what is DTI useful for
diagnoses
functional brain imaging
-fMRI (+ BOLD)
-MEG
-MSI
**fMRI
based on METABOLIC ACTIVITY (OXYGEN-DEPENDENT) of the brain
-ideal to determine which areas of the brain are metabolically active (functioning) when performing a certain task, such as reading or speaking
**blood oxygen level-dependent (BOLD)
when neurons are active, they require more oxygen so they can function, which is varied by the blood
-with BOLD fMRI we are basically tracking blood flow; measures brain activity by detecting changes in blood oxygenation levels
**magnetoencephalograhy (MEG)
records the magnetic consequences of the brain’s electrical activity
fMRI or MEG provides greater temporal resolution
MEG
magnetic source imaging (MSI)
combines structural MRI with MEG
analyzing complex behavior
-complex behaviors such as perception, language, emotions, consciousness, memory
-imaging techniques, such as fMRI can be combined with the principles of cognitive neuroscience, which focuses on the underlying structural + functional representations manifesting as behaviors
